1. Field of the Invention
This invention relates to an air bag inflation gas generator to feed combustion gas for inflation of air bags such as air bags for absorbing collision shocks, life jackets, rafts, and escape chutes.
2. Description of the Prior Art
A prior shock absorber to protect a passenger car driver from shocks at collision accidents comprises an air bag, for example, having a capacity of 60 liters and a gas generator to inflate the air bag with gas. At a collision accident of a passenger car, explosives or other gas generating agents having a similar composition thereto, which are charged in the gas generator, are ignited and burnt to produce some gas. The air bag is instantaneously inflated by the resultant gas for driver protection against any collision shocks, which can avoid possible serious injury.
FIG. 11 shows a prior air bag inflation gas generator disclosed in the Japanese Patent Application Laid-open No. 155857/1990. In the drawing, the reference numeral 1 shows a combustion chamber containing a plurality of gas generating agents 2 in the laminated state.
The gas generating agents 2 are a circular plate having a through hole 3 at the center, and the through hole 3 accommodates an ignition agent 4.
These gas generating agents 2 are accommodated in a concealed container 5. At the center of this concealed container 5, a concave part 6 is formed to be depressed toward the through hole 3 of the gas generating agents 2.
In the concave part 6 is provided an igniter 7 to burn the gas generating agents 2.
The combustion chamber 1 has a combustion chamber filter 8 along its inner wall. And, a plenum chamber 10 annually surrounds the combustion chamber 1 and receives gas flow through an orifice 9 from the combustion chamber filter 8.
The plenum chamber 10 contains a plenum chamber filter consisting of an upper filter 11 and a gas filter 12.
The plenum chamber 10 contains a gas outlet 13 to supply the gas flow from the gas filter 12 to an air bag.
In this type of air bag inflation gas generator, the powder in the igniter 7 burns when the igniter 7 is energized. The ignition agent 7 in turn causes the ignition agent 4 to burn and the gas generating agents 2 are burned. Gas from the gas generating agents 2 flows into the plenum chamber 10 through a combustion chamber filter 5 arranged along the inner wall of the combustion chamber 1. The gas is purified by the upper filter 11 and the gas filter 12 and flows into the air bag through the gas outlet 13. The air bag can be completely inflated within a very short time, for example, approximately 0.04 second.
That prior air bag inflation gas generator, however, has drawbacks that the combustion gas capacity of the gas generating agents 2 is limited and the purifying performance of the combustion gas is also limited.
Specifically, when the air bag for a front passenger seat is inflated, because the front passenger seat has a different riding environment from the driver seat and a passenger takes various positions, and when a child takes the front passenger seat, physical features are different from an adult, requiring, for example, an air bag to have a large capacity of 2.5 times of a conventional air bag for the driver seat. Therefore, it has been demanded that the combustion gas capacity of the gas generating agents is large and the gas generator for air bag inflation which can purify the large volume of combustion gas surely.
The present inventor has developed a gas generator for inflating an air bag which has remedied the conventional problems and filed patent applications (refer to Japanese Patent Application Laid-open No. 146842/1992, Japanese Patent Application Laid-open No. 146843/1992).
This air bag inflation gas generator, as shown in FIG. 12, has combustion chambers 21, 22 in which gas generating agents 20 are accommodated formed by a partition member 23 at both ends of a longitudinal outer cylindrical member 19 having gas outlets 18 formed at the middle section 17. And a cylindrical final filter 24 is disposed inside the middle section 17 of the outer cylindrical member 19. An intermediate filter 25 is disposed between the final filter 24 inside the outer cylindrical member 19 and the partition member 23. And, an orifice 26 is opened at a position on the side of the intermediate filter 25 of the partition member 23.
And, the combustion chamber 21 on one side and the combustion chamber 22 on the other side are connected with a fuse device 27 to ignite gas generating agents 20 in the combustion chamber 22 after the lapse of a certain time after starting combustion of gas generating agents 20 in the combustion chamber 21.
With this air bag inflation gas generator, the combustion gas capacity of the gas generating agents 20 can be largely increased than before, and a large volume of combustion gas can be surely purified.
With the fuse device 27, combustion of the gas generating agents 20 in the combustion chamber 22 is delayed, for example about 5-20 msec from the combustion of the gas generating agents 20 in the combustion chamber 21, so that at the initial inflation of the air bag, rapid flow of combustion gas into the air bag can be effectively prevented. Thus, impact against a passenger can be effectively eased.
However, such an air bag inflation gas generator uses the fuse device 27, so that there is disadvantages that the system becomes complicated and production costs increase.
FIG. 13 shows a conventional air bag inflation gas generator shown in Japanese Patent Application Laid-open No. 297336/1989. In the drawing, the reference numeral 28 indicates a longitudinal outer cylindrical member. This outer cylindrical member 28 has a plurality of gas outlets 29 formed in one side of the outer periphery.
At the center of the outer cylindrical member 28, pellet gas generating agents 30 are accommodated and, a cylindrical purifying filter 31 is disposed between the gas generating agents 30 and the outer cylindrical member 28.
On the gas outlets 29 side on the inside of the purifying filter 31, substantially semicircle barrier member 32 is disposed.
With the above air bag inflation gas generator, when the gas generating agents 30 burn, combustion gas from the gas generating agents 30 flows, by the action of the barrier member 32, opposite from the gas outlets 29 formed in the outer cylindrical member 28 and collides against the outer cylindrical member 28, turns its direction to pass through the purifying filter 31 for purification, then flows into the air bag through the gas outlets 29, and completely inflates the air bag in a short time.
However, with such a conventional air bag inflation gas generator, when the gas generating agents 30 burn, by the action of the barrier member 32, all combustion gas flows in the opposite direction from the gas outlets 29 formed in the outer cylindrical member 28, collides against the external cylindrical member 28 and turns its direction and is purified mainly at the opposite position of the barrier member 32 in the purifying filter 31, so that there is an disadvantage that the purifying filter is not entirely and effectively used.